1. Field of the Invention
The invention pertains to a socket mechanism having a flexible coupling therein for driving a bolt or nut, or like fastening piece, that is used particularly with a vertical type powered bolt/nut driving apparatus. The socket mechanism is so constructed that a reasonable amount of lateral misalignment between the object bolt or nut and the drive shaft of the driving apparatus can be permitted.
2. Description of the Prior Art
A powered bolt/nut driving apparatus is used with a work piece, such as a socket, that engages with a bolthead of a bolt or a nut that is rotated by the apparatus.
However, the center axis, or the rotating axis, of the socket, or other type of work piece actually used, and the center axis of the object fastening piece which the socket engages with (i.e. the bolthead or nut) are often laterally misaligned with each other. The presence of such misalignment is rather common, and, therefore, various ideas have been introduced for coping with such problems.
FIG. 5 perspectively shows a part of a conventional generally cylindrically-shaped flexible-coupling type socket 50 and a part of a bolt 51 that is to be rotated with the socket 50. FIG. 6 is a diagrammatic under view particularly showing relative positions of the socket 50 and the bolt 51 that are laterally misaligned with each other. The socket 50 integrally has a pair of downwardly projecting lugs 50j on diametrically opposing sides of a bottom end 50b thereof. The bolt 51 integrally has a bolthead 51h with a pair of wings 51w extending toward diametrically opposite directions. The inside diameter of the socket 50 is substantially greater than the diameter of the bolthead 51h but is smaller than the total tip-to-tip length of the wings 51w. Characters "Cs" and "Cb" in FIG. 6 denote diametric centers of the socket 50 and the bolthead 51h, respectively.
In FIG. 6, the socket 50 and the bolt 51 are horizontally off-centered from each other by dimension .delta., and the bolthead 51h is in contact with the inside wall surface and one of the lugs 50j of the socket 50. The dimension .delta. is the maximum limit of allowable misalignment within which the socket 50 can engage with the bolt 51. The allowable limit (.delta.) of the misalignment is a difference between the radii of the internal diameter of the socket 50 and the diameter of the bolthead 51h, as shown in FIG. 6. The socket 50 can engage with and rotate the bolt 51 overcoming a center misalignment therebetween as long as the internal diameter of the socket 50 is sufficiently larger than the diameter of the bolthead 51h and the tip-to-tip length of the lugs 50j is greater than the internal diameter of the socket 50. Needless to say, the socket 50 with lugs 50j, as shown in FIG. 5, will also be able to rotate a wing-nut similar to the bolthead 51h with wings 51w shown in FIG. 5.
(Problem to be Solved by the Present Invention)
Bolts with wing-heads, wing-nuts and sockets therefor having lugs are, however, less popular and not readily and economically available for a variety of applications. A particular application may require a special combination of bolthead (or nut) and socket having special shapes and dimensions that may not be readily available in the market. Conventional flexible-coupling type bolt (or nut) driving sockets tend to have disadvantages in availability and economy.
On the other hand, the bolts having hex boltheads and hex nuts are most commonly and widely used in the industries. They are readily available in various types, sizes and materials at comparatively low costs. However, virtually no center misalignment is allowed between a conventional socket designed for driving a bolt having hex bolthead or a hex nut before the socket engages with the nut or bolthead. Nevertheless, it is not an easy task to position a drive shaft of a vertical type powered driving apparatus without any lateral misalignment with the object bolt or nut.